1. Field of the Disclosure
The present invention relates to an electrophoretic display device, and more particularly to an electrophoretic display device and a method for manufacturing the same to enhance both driving stability and display quality, with improved production efficiency.
2. Discussion of the Related Art
In general, an electrophoretic display device refers to a device capable of displaying images using electrophoresis wherein colored charge particles are moved by an electric field applied from the outside. Here, ‘electrophoresis’ means a phenomenon that charged particles are moved in an electrophoretic dispersion liquid (electrophoretic ink) by coulomb forces when an electric field is applied to the electrophoretic dispersion liquid having the charged particles dispersed therein.
An electrophoretic display device using electrophoresis has a bistability that allows original images to be displayed for a relatively long time even if an applied voltage is removed. In other words, the electrophoretic display device can maintain a specific screen for a relatively long time without voltages being continuously applied thereto. As a result, the electrophoretic display device may be applied to e-books which do not require quick changes of screens.
Moreover, an electrophoretic display device has no dependence on viewing angle and can provide images that are comfortable to eyes and remarkably similar to paper, unlike a liquid crystal display device. As a result, demands for the electrophoretic display devices have been increasing as next generation display devices because electrophoretic display devices are flexible, have low power consumption and are eco-friendly.
FIG. 1 is a sectional view illustrating a structure of a display device according to the related art.
With reference to FIG. 1, an electrophoretic display device includes lower and upper substrates 10 and 20 bonded to each other with an electrophoretic film 30 disposed between the lower substrate 10 and the upper substrate 20. The lower substrate 10 includes a plurality of pixel electrodes (not shown) opposed to a common electrode 22 formed on the upper substrate 20 and a plurality of thin film transistors (TFT, not shown) to supply voltages to the plurality of the pixel electrodes as switching devices. The electrophoretic film 30 includes a plurality of microcapsules 32 having charged particles and a dielectric solvent and an adhesive layer 34 configured to protect the plurality of the microcapsules and to attach the electrophoretic film to the lower substrate 10.
Here, the microcapsule 32 includes the dielectric solvent and charged particles. Some of the charged particles are charged to have a positive (+) pole and the others are charged to have a negative (−) pole. When an electric field is formed between the pixel electrodes of the lower substrate 10 and the common electrode 22 of the upper substrate 20, the charged particles provided in the microcapsule 32 are moved within the dielectric solvent, thereby presenting an image.
According to the electrophoretic display device of FIG. 1, the upper substrate 20, the lower substrate 10 and the laminated electrophoretic film 30 are manufactured. After that, the electrophoretic film 30 is disposed between the lower substrate 10 and the upper substrate 20.
The electrophoretic film 30 is kept and carried, with a release film attached to an adhesive layer 34. Just before the electrophoretic film 30 is laminated onto the lower substrate 34, the release film is eliminated. After that, the adhesive layer 34 is attached to the lower substrate 10 in a laminating process.
As described above, the manufacture process of the electrophoretic display device is quite complicated because the lower substrate 10, the upper substrate 20 and the electrophoretic film 30 have to be manufactured separately. As a result, the manufacture of the electrophoretic display device will require much time and productivity might deteriorate disadvantageously. Also, the electrophoretic film 30 additionally has to be manufactured and production cost might be disadvantageously increased.
To overcome such disadvantages of the electrophoretic display device, technology enabling the electrophoretic layer internalized on the lower substrate has been under development. However, a structure and a manufacturing process technology for internalizing the electrophoretic layer on the lower substrate have not matured to solve existing problems. As a result, it is difficult to apply the technology to actual production.